US3453932A - Method and apparatus for forming metal parts - Google Patents

Description

METHOD AND APPARATUS FOR FORMING METAL PARTS J. D. WORKS ETAL July 8, 1969 Sheet Filed Dec.

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METHOD AND APPARATUS FOR FORMING METAL PARTS Filed Dec. 5, 1966 Sheet 2 of 12 July 8, 1969 J. D. WORKS ETAL 3,453,932

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METHOD AND APPARATUS FOR FORMING METAL PARTS Filed Dec, 5, 1966 Sheet 6 of 12 July 8, 1969 J. D. WORKS ETAL METHOD AND APPARATUS FOR FORMING METAL PARTS Sheet- Filed Dec.

July 8, 1969 J. D. WORKS ETAL METHOD AND APPARATUS FOR FORMING METAL PARTS c9 of 12 Sheet Filed Dec. 5, 1966 July 8, 1969 J WORKS ETAL 3,453,932

METHOD AND APPARATUS FOR FORMING METAL PARTS Filed Dec. 1966 Sheet 9 of 12 laweiziofls: VA 22 Yam METHOD AND APPARATUS FOR FORMING METAL PARTS July 8, 1969 J. D. WORKS ETAL sheet Q or 12 Filed Dec. 5

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METHOD AND APPARATUS FOR FORMING METAL PARTS I July 8, 1969 Sheet of 12 Filed Dec. 5, 1966 Izwezaiom: V4, I? Mal 5* m 7am July 8, 1969 J. D. WORKS ETAL 3,453,932

METHOD AND APPARATUS FOR FORMING METAL PARTS Sheet AZ Filed Dec. 5, 1966 l I 11V Inveni'ow United States Patent 3,453,932 METHOD AND APPARATUS FOR FORMING METAL PARTS John D. Works, Lexington, Donald H. White, Everett, and Alan M. Campbell, Weston, Mass., assignors to AMW Corp., Arlington, Mass., a corporation of Massachusetts Filed Dec. 5, 1966, Ser. No. 599,167

Int. Cl. B23f 23/08; B21g 3/32; B21k 27/00 U.S. CI. 9011 7 Claims ABSTRACT OF THE DISCLOSURE An apparatus for automatically manipulating electrodes of the class employed in resistance welding, means being provided for automatically positioning electrodes in a holding mechanism of a turret to present the extremity of the electrode for tip dressing or refinishing with a minimum removal of metal.

This invention relates in general to machining operations and, more particularly, to methods and apparatus for machining electrodes and various other relatively small workpieces. In one specific aspect the invention is concerned with an apparatus for automatically dressing electrodes of the class employed in resistance welding.

A common form of resistance welding is spot welding which is used extensively for joining sheet metal parts to provide both low cost and high volume products. In spot welding a type of electrode usually employed consists in a cylindrical body of high conductivity copper alloy. At one end the electrode is recessed to form a coolant hole and at the other end the electrode is formed with a tapered tip which terminates in an electrode face of some predetermined size and shape. The coolant hole end of the electrode may also be tapered for holding purposes in some cases.

The quality of a spot welding operation depends upon the symmetry, smoothness and cleanliness of the tapered electrode tips and it will be understood that the spot welding process tends to cause a rapid deterioration of the electrode tip making it necessary to refinish the tapered end of the electrode rather frequently. Since the cost of electrodes is appreciable, it is important to carry out tip dressing or refinishing quickly and with a minimum removal of metal.

It is a chief object of the invention, therefore, to provide an improved apparatus for automatically machining electrodes and various other small workpieces efficiently and at a relatively high rate of speed.

Another object of the invention is to provide an apparatus which can reform a used electrode tip accurately and with a minimum removal of metal in order to produce a desired electrode tip face.

Another more specific object of the invention is to combine with an adjustable rotary cutting tool means for containing and periodically feeding electrodes into a loading magazine, means for advancing electrodes from the loading magazine to the cutting tool in a completely automatic manner and means for conveying dressed electrodes away from the cutting tool to a discharge station.

Still another object of the invention is to design a feed mechanism in which used electrodes occurring in a random state of orientation in a container are advanced along a desired path of travel and subjected to a novel step of positioning by means of which all electrode tips are arranged in a forwardly disposed state of orientation.

Still another object of the invention is to provide a method of sequential handling of workpieces in which method a plurality of workpieces are simultaneously engaged at several different points in the machine and mOved through separated stations in the apparatus.

The nature of the invention and its other objects and novel features will be more fully understood and appreciated from the following description of a prefered embodiment of the invention selected for purposes of illustration and shown in the accompanying drawings, in which:

FIGURE 1 is a side elevational view showing the electrode dressing apparatus of the invention;

FIGURE 2 is another side elevation showing the apparatus from an opposite side to that viewed in FIG- URE 1;

FIGURE 3 is a plan view;

FIGURE 4 is an enlarged detail plan view of a p rti n of the structure shown in FIGURE 3;

FIGURE 5 is a perspective view illustrating a base for the electrode dressing machine and further indicating components of the machine in a partly assembled state;

FIGURE 6 is a cross section taken on the line 6--6 of FIGURE 3;

FIGURE 7 is a detail cross section taken on the line 77 of FIGURE 6;

FIGURE 8 is a cross section taken on the line 8-8 of FIGURE 3;

FIGURE 9 is a detail cross sectional view of electrode orienting apparatus;

FIGURE 10 is a detail cross sectional view similar to FIGURE 9 but showing an electrode in a reversed position;

FIGURE 11 is a cross sectional view of a loading magazine with portions of an indexing wheel member shown in elevation;

FIGURE 12 is a fragmentary plan view of the loading magazine shown in a position to deliver an electrode to an adjacent indexing member;

FIGURE 13 is an enlarged detail cross sectional view of adjustable electrode holding means mounted in indexing wheel member;

FIGURE 14 is a side elevational view of a used electrode prior to undergoing a dressing operation;

FIGURE 15 is a side elevational view of an elec rode shown after a dressing operation has been carried out;

FIGURE 16 is a cross sectional view taken on the line 16-16 of FIGURE 6 indicating an electrode retained in an indexing member in a position to undergo a machining operation;

FIGURE 17 is a detail view of rotary table mechanism employed in the apparatus of the invention;

FIGURE 18 is a detail elevational View of electrode ejecting mechanism;

FIGURE 19 is a detail perspective view of a cutting tool for carrying out the machining of an electrode tip;

FIGURE 20 is a diagrammatic view illustrating pneumatic control apparatus of the invention;

FIGURE 21 is a wiring diagram employed for electrically controlling various sequence of operations in handling electrode member; and

FIIGURE 22 is a detail elevational view of a control pane With the foregoing objectives in mind, we have devised a method and apparatus for automatically machining or dressing used electrodes wherein a special rotary cutting mechanism is employed. This cutting mechanism is generally denoted in the drawings by the reference character R and is supported for rotation about a horizontal axis on a suitable support member as hereinafter described in detail.

Selective control of operation of the rotary cutting mechanism R is combined with a series of electrode handling operations which are also carried out automatically to bring successive electrodes into and out of engagement with the cutting mechanism. The several electrode handling operations are further designed to take place in a predetermined sequence which can be regulated and controlled in a unique manner.

As noted above, the invention will be described with particular reference to machining used spot welded electrodes to provide the electrode with dressed tapered tips. It should be understood, however, that the invention is not intended to be limited to machining electrodes but may be practiced in connection with working a wide range of other forms of workpieces.

With respect to spot welding electrodes specifically, it is pointed out that these devices are customarily made of a high conductivity copper alloy. As shown in FIGURES 14 and 15 one common type may consist of a eylindrically shaped member. Electrodes of this shape may have, for example, a diameter of .483 inch and lengths ranging from 2 to inches. At one end the cylindrically-shaped member is formed with a tapered contact tip and at the other end the electrode is formed with an axially coolant hole, and the coolant hole end of the electrode may in some cases be tapered for holding purposes.

It will be appreciated that when used electrodes of the form described are collected in a container, they necessarily occur in a randomly oriented state. It will be apparent therefore that in order to carry out continuously an automatic machining operation on successive electrodes, it is necessary to provide means for feeding successive electrodes from the container and thereafter orienting each of the electrodes so that the worn contact tip of each succeeding electrode will be presented to the cutting tool in a correctly disposed position. In addition, the apparatus must also be capable of handling a range of lengths and diameters occurring with different forms of electrodes.

We have devised a method in which the step of orienting electrodes furnished from a container is accomplished quickly and efliciently and several other electrode handling operations are performed simultaneously. Each operation is carried out in a predetermined interval of time which is chosen with reference to the interval of time normally required to dress a worn electrode tip by means of the rotary cutting mechanism R noted above. This time interval may, we find, be in a range of from six to ten seconds, for example, with one typical size of electrode as noted above with which the invention is concerned.

For operating within a time interval of the range of magnitude indicated, we have combined the rotary cutting mechanism R with a plurality of electrode handling stations which are compactly arranged around mechanism R and through which successive electrodes may be passed in a rapid and controlled manner. By means of this arrangement of electrode handling stations a substantially continuous operation is made possible, and each star tion may be selectively operated in response to interlocking controls of a desirable nature.

In addition to the basic rotary cutter mechanism R noted, another important component of the invention is a rotatable indexing member which is constructed with a. plurality of novel electrode holding collets in which worn electrodes may be supported in a horizontally disposed position. The indexing member is arranged to index each collet through a series of stations including a loading station, a cutting station which is in register with the rotary cutting mechanism R and an unloading station for discharged finished electrodes. Cooperating with the indexing member is an independently controlled reciprocating drive for moving the rotary cutting mechanism R into and out of a cutting position with respect to an electrode positioned in the cutting station described.

Additional components of the apparatus include an electrode furnishing mechanism for periodically supplying electrodes to the indexing member and an electrode orienting device as noted above for positioning successively fed electrodes with their worn tips in a forwardly 4 disposed position relative to collets in the rotary indexing member. Also associated with the rotary indexing member are collet operating means and injector and ejector devices for moving electrodes into and out of the collets in the indexing member. These several components are described in detail.

As shown in FIGURES l to 5 inclusive, numerals 4, 6 and 8 denote uprights for a supporting structure which is formed at its upper side with a fiat table section 2 on which the several components of the invention noted above may be secured in cooperating relationship to one another. The table section 2 is most clearly shown in FIG- URE 5 and as will be seen from an inspection of this figure is formed of rectangular shape with a channelled edge portion 2a. Electrical control boxes P1 and P2 are mounted at one side of upright 44 and a third operator control box P3 is mounted at the upper side of table section 2.

In one preferred form the table 2 is made of steel or other suitable material in a thickness suitable for having solidly bolted thereto a number of holding brackets as shown in FIGURE 5 by means of which the several components of the invention are arranged in cooperating relationship to one another as hereinafter disclosed in detail. In FIGURE 5 several of the components are shown removed from the table 2.

Referring more in detail to FIGURES 1-3, the rotary cutting mechanism R is shown mounted at one end of table 2. Centrally mounted on the table section 2 in front of cutting mechanism R is an indexing apparatus of the invention which generally includes an indexing member and pneumatic work feed means for periodically rotating the indexing member in a predetermined manner. The pneumatic work feed means, without the indexing member attached, is shown in FIGURES 5 and 17. Numeral 10 denotes the indexing member which is illustrated in FIGURES 1 to 3, 6, 7, 8, l1, 12, 13 and 16 attached to the work feed means for rotation about a horizontal axis.

The work feed means for producing indexing movement of member 10 is generally indicated by the arrow F (FIG- URE 5) and in one preferred form may comprise a solenoid operated pneumatic drive device such as is manufactured and sold by the Bellows-Valvair Company of Akron, Ohio.

In FIGURES 5 and 16 the apparatus F is shown in further detail and includes a housing body W which is supported on bracket means 67 in a raised position. Projecting from one side of the housing body is a horizontal shaft 13 on which is received a rotatable plate element 14 secured by nut 13a (FIGURE 5 Indexing component 10 is attached to the plate element 14 in some convenient manner as by bolts 16 and 18 as is more clearly shown in FIGURE 16. Periodic rotation of plate 14 and attached indexing member 10, is accomplished by a pneumatically operated ratchet machanism contained within the housing W, details of which are more fully shown in FIGURE 17.

A reciprocating rod 26 acts through a linkage 24 and a pawl 22 to engage and turn ratchet wheel teeth 20 of a ratchet 15. The rod 26 is periodically advanced and retracted by a fluid pressure actuated device 28 in turn regulated through valves 17 and 19 by control member 29 (FIGURE 17).

The indexing member 10 is formed of a material such as steel or other suitable material and is of a diameter appreciably greater than the rotatable plate 14 as is more clearly indicated in FIGURE 16 to provide peripheral portions extending well beyond plate 14.

In accordance with the invention, we provide around the outwardly projecting peripheral portion of 10 a plurality of spaced collet apertures preferably occurring at sixty degree intervals. The central axes of these collet apertures are arranged to extend along lines located outside of the peripheral edge of plate 14 so as to provide a substantial clearance for moving electrodes into and out of the collet apertures as hereinafter disclosed. In the collet apertures noted are received special electrode holding collet assemblies which are illustrated in FIGURE 16 and also in more detail in FIGURES 6, 7, 8 and 13, on a somewhat enlarged scale. As indicated in FIGURE 6 especially, the several collet assemblies are denoted by the reference characters C1, C2, C3, C4, C5, C6 and as shown at the front side of indexing member 10 normally occur in a closed or clamping position. The collet assemblies are all of similar construction and may, for example, be of the draw-in type to provide for releasably clamping an electrode.

In combination with the draw-in collets described, we provide in member 10 a plurality of spring-loaded collet unclamping units for selectively opening or unclamping each of the collets C1, C2, C3, C4, C5, C6. These several collet unclamping units are illustrated in FIGURES 1, 2 and 3 and in more detail in FIGURES 6, 7, 8 and 13 and are denoted by the reference characters G1, G2, G3, G4, G5, G6. The spring-loaded collet unclamping unit for collet 4, shown in FIGURE 7, will be described in detail with it being understood that similar parts are pro vided for all of the remaining collet unclamping units.

As noted in FIGURE 7, a bearing 30 located transversely through the indexing member 10 is secured by fastenings as 32 and has slidably received therein the collet C4. The collet C4 is of the conventional draw-in type having split clamping sections which open and close in response to movement of sleeve means 31 in bearing 30. As shown in FIGURE 7 the collet sleeve means 31 projects outwardly from the member 10 and fixed on this projecting end is a collar 34 to which is pivotally secured by pins 36 an end of a lever 37 (FIGURE 8). The lever 37 is in turn pivotally mounted on a pivot rod 38 extending between two holding members 40 and 42 in member 10 as is also shown in FIGURE 8.

At an opposite end lever 37 is formed with a clevis portion 44 pinned to a spring-loaded rod 46. As shown in FIGURE 7 the rod 46 is slidably received through a hollow bearing 48 in which is compressibly maintained a spring 50 secured by a collar 52 and nut 54 on a threaded end 52 of rod 46. It will be apparent that by engaging an end face of rod 46 and compressing the spring 50 inwardly, the lever 37 may be pivoted about the pivot rod 38 and the collet C4 may be moved into an open position to receive an electrode E as suggested in FIGURE 7. FIGURE 14 illustrates a worn electrode E and FIG- URE illustrates electrode E in a finished or dressed condition. A pneumatically operated actuator 60 hereinafter described in further detail is indicated fragmentarily in FIGURE 7 and is movable in the direction of the arrow shown to contact an end face 53 of rod 46 and unclamp the collet.

Electrodes are moved into the collets described from a vibratory type feed device generally denoted by arrow H and having a hopper 61 in which a quantity of electrodes may be received. It should be understood, however, that the invention is not limited to a vibratory feed device and we may desire to utilize various other electrode furnishing means especially when handling other types of workpieces.

Considering in detail the preferred vibratory type feed shown in the drawings, the hopper 61 may, for example, be mounted on a base 62 secured at one side of the table section 2 as shown in FIGURES l3 inclusive. Syntron is the name of the vibratory feed type machine shown in the drawings and this machine is manufactured by The Syntron Company.

As noted in FIGURES 1, 2 and 3, the hopper 61 is provided with an inclined circular track 64 along which used electrodes occurring in random orientation are progressively moved in a conventional vibratory feed manner. The inclinded portion of track 64 extends downwardly over one side of the table section 2 as shown in FIGURES 2' and 3 and constitutes a guideway for conducting spaced apart electrodes to an electrode sensing and positioning device.

As indicated diagrammatically in FIGURES 1-3 inclusive, worn electrodes supplied from the hopper 60 move down the track 64 with the tips in random orientation. Thus as shown in FIGURE 3 electrode E1 is moved with its tip in a correct forward position While electrode E2 is in a reversed position and must be turned end for end before being delivered to a collet in the indexing member.

For this purpose we have devised the special electrode sensing and positioning device referred to above. This device is generally indicated by arrow J and the relatively narrow conduit member 66 connects the receptacle with the lower end of track 64 as shown in FIGURE 4. The conduit member 66 is fixed to a frame piece 68 in turn rigidly held to the top of bracket 67 as shown in FIG- URES 1 and 2. Electrodes are guided from conduit 66 into box shaped enclosure 66a more clearly shown in FIGURE 4.

The enclosure 66a is provided at its lower end with a sensing and holding stud 74 and is further constructed at its bottom side with a sliding trap door 69 most clearly shown in FIGURES 4, 9 and 10. This trap door 69 is movable in the frame piece 68 and slidably displaced into the dotted line position shown in FIGURE 4. Opening and closing the trap door 69 is accomplished by means of a pneumatically operated cylinder and actuating plunger apparatus 72 secured at one edge of the frame piece 68 and attached to a bottom edge of the trap door 69 as shown.

The sensing and holding stud 74 is fixed at the lower end of the enclosure 66a in a position. to readily engage in the coolant hole of an electrode which moves downwardly into the enclosure body in an incorrect position as shown in FIGURE 9. As will be seen from an inspection of FIGURE 4, the trap door 69 is formed with a wedge shape and has an angularly extending edge 69a. As this member is retracted into the dotted line position of FIGURE 4 a drop out opening 0 is progressively formed as shown in FIGURE 4.

Thus an electrode occurring in an incorrect or reversed position is sensed by stud 74 and the coolant hole is engaged over pin 74 to become held in the enclosure 66a until the trap door 69 reaches a fully retracted position as shown in dotted lines in FIGURE 4. At this point the opposite unsupported end of the electrode will, by gravity, drop down while the engaged end is still supported on stud 74 and, therefore, the electrode tips downwardly and becomes turned over upon itself as suggested in dotted lines in FIGURE 9.

In this turned position the electrode is received in a curved guidechute 76 which is mounted on a bracket 75 on table 2 (FIGURE 5) so as to occur immediately below trap door 69. The electrode is thus turned into a correctly oriented position with its tip forwardly disposed with respect to its path of travel and each succeeding electrode occurring in a reversed position will be similarly oriented.

In the case of an electrode which is already in a correctly oriented position as it approaches the enclosure 66a, the coolant hole of the electrode occurs in a reversed position and cannot engage over sensing stud 74. As the angular edge 69a is retracted, the drop out opening 0 increases in width with that portion of the opening at the lower end of the member 66a reaching its maximum size first. This results in the upper end of the electrode being temporarily supported with the lower end being caused to drop by gravity forces into the chute 76 with its tip in a correct forwardly disposed position as illustrated in FIGURE 10.

It will be seen therefore that successive electrodes regardless of the position in which they may occur in approaching the conduit 66 will be advanced through the chute in a correctly oriented position to approach the indexing member 10.

Electrodes reaching the chute 76 in a correctly oriented position are conducted into a novel electrode loading magazine M which is located closely adjacent to the indexing member 10 and secured in some suitable manner as by bolts anchored in the bracket member 67. The magazine M is illustrated in FIGURES l3, 6l1 and 13 of the drawings and includes an upper guide portion 80 which as shown in FIGURE 12 receives electrodes leaving the lower end of chute 76 and conducts them along an inclined bottom section of the magazine M with their longitudinal axes disposed parallel to the central axes of the collet apertures in the indexing member 10.

It is pointed out that the magazine M provides storage for a plurality of electrodes E1, E2, E3, E4, E furnished from the vibratory feed earlier described. It is intended that the rate of feeding may be regulated with respect to the interval of time required for dressing an electrode in the rotary cutting mechanism R so that a desired number of electrodes may be maintained in the mechanism at all times.

The magazine M thus provides a means of loading electrodes into the collets at a controlled rate. As shown in FIGURE 6, the inclined bottom surface of magazine M is arranged to support an electrode in a lowermost position which is in register with the collet C3 in the position of indexing member shown in FIGURE 6. The arrangement described is further illustrated in more detail in FIG- URES 11 and 12 and as shown in the latter figure there is provided an elongated loading ram or plunger 84 which is arranged to be moved forwardly and rearwardly by means of a pneumatic actuator 86. The actuator 86 is secured along one side of a bracket 88 as shown in FIGURE 3. It will also be observed that the loading ram 84 further operates a limit switch S1 hereinafter described in more detail.

With the collet C3 engaged by collet opening means G3 and occurring in an opened position, forward movement of loading ram 84 transfers the lowermost electrode E1 through the collet C and into contact with the tip of limit switch S2 and then the stop 90 as suggested in FIGURES 12 and 13. It will be understood that operation of the components in the manner described is controlled electrically and in a predetermined sequence as illustrated in the electrical Wiring diagram shown in FIGURE 2. The pneumatic control diagram of FIGURE also illustrates the pneumatically operated devices employed in the invention. Further details of the circuit operation are described at a later point in the specification.

The collet unclamping means G3 is actuated by plunger 60 and pneumatically operated cylinder 60a also controlled through the above-noted circuit. The reciprocating members 60 and 60a are secured on the table 2 at a point beside the rotary cutter mechanism R as shown in FIG URE 3.

Referring more in detail to the rotary cutter mechanism R, we have devised a special cutter holder 93 which is shown on an enlarged scale in FIGURE 19. The cutter holder comprises an electrode enclosure body having a ring portion 96 and a replaceable cutter element 94 formed with an angled cutting edge 92. The enclosure ring 96 is formed with an aperture 98 through which an electrode may be guided into a desired cutting position relative to the angled cutting edge 92.

It is pointed out that the particular cutter holder construction described functions to conveniently guide and hold an electrode in a registered position to be engaged by the angled cutting edge 92. Also this particular cutter holder arrangement is adapted for use with various lengths of electrodes since the electrode moves against the stop earlier described and controls adjustment of the cutter holder first at rapid speed and then at slow speed into contact with the electrode. The cutter assumes therefore a constant setting regardless of the length of electrode introduced into the collet. It is also noted that the particular rotary cutting operations accomplished by the angled cutting edge 92 can be precisely adjusted to remove only a limited amount of material necessary for obtaining a desired tip contour and this controlled removal of metal is carried out efficiently and in a very small interval of time.

When the electrode E1 has been received through the collet C3 the collet unclamping actuator retracts and the indexing member 10 under control of the electrical operating circuit means earlier noted, indexes the collet C3 and electrode E1 through a sixty degree are of travel into register with the enclosure ring 96 of cutting mechanism R as suggested in FIGURE 7. The cutter holder 93- and cutting element 94 then advance by means of conventional two-speed power driving means D, first at a rapid rate and then at a slow rate, until the electrode E1 has been received through the opening 98 in the ring portion 96 and brought into engagement with the cutting edge 92 of cutter 94.

The cutting edge is then revolved around the worn tip of electrode E1 for the predetermined interval of time earlier disclosed to carry out a desired refinishing of the metal so as to meet reshaping requirements and to avoid excessive removal of metal while providing a desired tip contour. At the end of this interval the cutter edge 94 and its holder are retracted to a starting position, a limit switch S3 is operated to retract the collet unclamping unit and the indexing member 10 indexes the finished electrode E1 and collet C3 into a position for ejection of the electrode into a discharge chute 99 extending downwardly over an edge of the table 2 as shown at the upper side of FIGURE 3.

Electrode ejecting apparatus is illustrated in FIGURES 3, 8 and 18 and includes a collet unclamping unit together with a pneumatically operated actuating plunger for ejecting the electrode from the collet when opened. As shown in FIGURE 3, numeral 100 denotes the plunger controlled by a pneumatically operated actuator 102 and electrical switch means S4 therefor. When the plunger 100 is advanced as shown in FIGURE 18, the contacted collet is opened releasing the electrode therein. At an opposite side of the indexing member 10 is an electrode ejecting ram 104 also controlled by a pneumatically operated device 106 and limit switches S5 and S6. Movement of the ram 104 into contact with the electrode ejects this member from the collet and the finished electrode falls into the chute 99.

It will be apparent that the indexing member 10 may be set to move through a desired arc of rotation at predetermined intervals and each time the indexing movement takes place another electrode is advanced to a loading position, a previously loaded electrode moves to the machining station, and a previously machined electrode moves to the ejection station. Also during the period of operation of the rotary cutting mechanism with the indexing member at rest, an electrode is loaded and clamped in a preceding collet and another finished electrode is unclamped and ejetced from still another collet.

It will also be understood that the entire cycle of operations described are carried out under the control of the operating circuit earlier noted. This circuit includes a number of limit switches some of which have been indicated and are operated mechanically by movement of the actuating devices. Cooperating with these mechanically operated limit switches are manual panel switches and relays within the circuit control boxes P1, P2 and P3. Included in the several pneumatically operated limit switches are switches S1, S2, S3, S4, S5, S6, S13. Additional switches which are operated within the control box include switches S7, S8, S9, as well as other manually operated switches as hereinafter described in the detailed description of the operating circuit.

Considering the control circuit in detail, attention is directed to FIGURE 21. Closure of safety switch S13 applies 230 v. S-phase power to the unit. One phase of this supply energizes the primary of transformer T1 which, in turn, energizes the primary of transformer T2 at 115 v. The secondary of transformer T2 delivers 12 v. for most of the control functions. Initially, indicator light L1 (Turn to Start) is on, energized through NC contact K14. If the main air line valve is on and pressure is above the minimum required value of 70 p.s.i. switch S12 NO contact closes and indicator lights L3 and L4 (Air ON) are on. Manual switch S10A is then momentarily turned counterclockwise and released. This energizes a relay coil which then holds in through NO contact KIA. NC contact KlA opens and indicator light L1 goes off. Indicator light L2 (Push to Stop) also goes on at this time. If the previous shutdown was normal switch S7 NO contact would be closed indicating the drilling unit to be retracted, switch S5 NO contact would be closed showing the ejection actuator to be retracted, switch S14 NC con tact closed indicating no electrode in the ejection station and switch S1 NO contact closed indicating the load actuator to be retracted. As a result of switch S7 being closed indicator light L8 (Ready to Clear) would be on and indicator light L6 (Ready to Index) would be on since switches S7, S5, S14 and S1 were also closed. Under these circumstances, momentarily closing manual switch 511B would cause indicator light L7 (Turn to index) to go on and also energize solenoid valve V8 retracting the rotary table actuator. Switch S8 (located in the rotary table) NC contact closes energizing relay coil K4 through switch S7 NO contact. The relay holds in through contact K4A. When this actuator reaches its limit it mechanically shifts to advance and indexes the table.

At the completion of the indexing operation switch S8 NO contact closes. This energizes relay coil K2. Contact K2A closes and, in conjunction, switch S2 NC contact which is closed, energizes solenoid valve V5 causing the load actuator to advance. Contact K2B closes energizing solenoid valve V1, advancing the drilling unit. Contact K2C closes energizing relay coil K3. As contacts K3A, B and C closes the drilling unit motor starts. Contact K3D holds relay coil K3 in. Contact K2D closes energizing solenoid valves V4 and V6 causing the ejection and unclamp actuators, respectively, to advance.

As the drilling unit advances, switch S7 NO contact opens, de-energizing relay coil K4 and indicator light L8. This also de-energizes relay coil K2. As the load actuator advances driving an electrode into the collet at the loading station, switch S1 NO contact opens. As the tip of the electrode reaches the mechanical stop it strikes switch S2 causing the NO contact to close and the NC contact to open.

Advance of the ejection actuator allows switch S5 NO contact to open and when it reaches its forward limit switch S6 NO contact closes. This action, in combination with S2 NO contact closure, turns indicator light L5 (Turn to Clear) on and energizes solenoid valve V3, causing the ejection actuator to retract.

As the unclamp actuators advance, switch S3 NC contact closes and when S2 NO contact and S6 NO contact are also closed, solenoid valve V2 is energized causing the unclamp actuators to retract.

As the ejection actuator retracts, switch S6 NO contact opens, turning indicator light S5 off. This is followed by switch S5 NO contact closing as the actuator reaches its limit.

Retraction of the unclamp actuators opens S4 NC contact and causes S4 NO contact to pulse, energizing solenoid valve V7. This results in the retraction of the load actuator. As the load actuator reaches its limit S1 NO contact closes.

Switch S14 NC contact remained closed during the initial cycle, and switches S5 NO and S1 NO are now closed. When the drilling unit retracts, closing switch S7 NO contact and pulsing switch S9 NO contact, solenoid valve V8 is energized, starting the second cycle.

Action during this and subsequent cycles is the same as described above as long as the magazine remains filled with electrodes except that as the rotary workfeed indexes, the finished electrode strikes switch S14 causing its NO contact to close and its NC contact to open. Closure of the NO contact energizes solenoid valves V4 and V6 causing ejection of the finished electrode and permitting switch S14 to return to its normal state. While it is open switch S14 NC contact prevents the rotary Workfeed from indexing. This is essential in case of loss of power to the machine after indexing has been initiated, but before ejection has commenced.

When the magazine is exhausted of electrodes the load actuator will advance to its limit, but switch S2 NO contact will remain open preventing retract of the unclamp and ejection actuators. The drilling unit will complete its machining cycle and retract, but indexing will not take place since switches S5 NO and S1 NO contacts are still open. However, when switch S7 NO contact closes indicator light L8 (Ready to Clear) goes on. Momentary closure of manual switch 811A will energize solenoid valves V2 and V3 causing the unclamp and ejection actuators to retract. As the unclamp actuators retract switch S4 NO pulses causing the load actuator to retract.

Switch S5 NO and S1 NO contacts are now closed, but switch S9 NO contact has pulsed previously so the cycle again stops with indicator light L6 (Ready to Index) on. Momentary closure of switch S11B now energizes solenoid valve V8, initiating the indexing cycle. The last electrode is ejected as before and action ceases with the Ready to Clear indicator on. Again momentary closure of switch S11A will cause the unclamp, ejection and load actuators to retract and the machine may be turned oif by momentarily depressing the Stop button, switch S10B.

It should be noted in the above description of the control circuit, that completion of various sequences of operation must take place before the next sequence can commence. This means that the cycle will continue automatically as long as pieces are supplied or until a malfunction occurs. Occurrence of a malfunction will simply cause the cycle to stop without damage to the machine. This is in contrast to timer controlled equipment Where each operation is stopped after a predetermined length of time, whether complete or not, and where malfunction may cause damage to or, at least,-require readjustment of the machine.

Another advantage of the control circuit utilized here over the timer programmed type is that it permits the fastest operation possible while assuring completion of each step. In addition, with a timer control, variations in conditions such as air line pressure or electrode machinability, for example, can disrupt the automatic cycle.

It is contemplated that the apparatus now described may be modified in various ways. For example, the apparatus may be utilized with other electrode diameters by changing the collet sizes and the diameter of the load and ejector rams. Further changes may include increasing the length of stroke of the pneumatically operated cylinder and varying the cutting interval to carry other handling operations for a variety of other workpieces of a similar composition. We may also employ other forms of feeding and delivery devices. For example the apparatus of the invention could be combined with delivery of finished workpieces into individual holders or compartments in a tote box or other container. Insertion of each electrode into the container would release a pawl on the equipment permitting the container to advance enough to accept the next electrode when finished. The same container could also attach to the loading magazine or orientor to allow automatic feeding of unfinished electrodes.

Use of the container described above would also permit elimination of the bulk type of feeder referred to under feeding. If the container is placed in suitable guides ahead of the orientor and an additional pneumatic actuator located behind it the actuator can be arranged to drive an electrode into the orientor in synchronism with the loading operation. When this actuator ram retracts, gravity or a pneumatic actuator will cause the container of electrodes to advance until the next electrode is in position to be driven into the orientor.

While we have shown and disclosed preferred embodiments of the invention, it should be understood that various other changes and modifications may be practiced within the scope of the appended claims.

We claim:

1. Apparatus for machining workpieces comprising a base, an indexing member supported on the base for rotation about a horizontal axis and formed with a plurality of spaced workholding collets, said indexing member including a plurality of spaced collet unclamping devices transversely located therethrough and operatively connected to respective collets, means for periodically turning the indexing member through a plurality of work supporting stations, an adjustable cutter mechanism mounted on the base at one side of the indexing member, means for concurrently moving workpieces into and out of holding positions in the said workholding collets at two of said work supporting stations including fluid pressure operated plunger means arranged to move into and out of engagement with the collet unclamping devices, said collets further including a collet adjusting sleeve projecting from one side of the indexing member and each of the collet unclamping devices including a lever element pivotally mounted on the indexing member, one end of the lever element being pinned to the collet adjusting sleeve and the opposite end of the lever being pivotally attached to a spring-loaded actuator rod transversely disposed through the indexing member, said actuator rod having an exposed end thereof projecting from the indexing member to present a contact surface for engagement by a respective fluid operated plunger, and means for simultaneously moving the cutter mechanism into and out of engagement with successive workpieces at a third work supporting station.

2. A structure according to claim 1 in which the fluid pressure operated plunger means is controlled by electrically operated circuit means and said electrical circuit means includes limit switches arranged in the path of travel of the said fluid operated plunger means to control advancing and retracting movement.

3. A structure according to claim 2 in which the means for moving workpieces into and out of holding positions further includes a magazine for receiving and supporting a plurality of workpieces with one of the workpieces being arranged in axial alignment with a collet aperture in the indexing member and fluid pressure operated loading plunger means for advancing said axially aligned workpieces into the collet aperture while the respective collet unclamping device is in an unclamping position.

4. A structure according to claim 3 in which the loading plunger means includes limit switch means arranged in its path of movement and connected to the electrical operating circuit means to interrupt machine operation when no workpiece is in the said axially aligned loading position.

5. A structure according to claim 1 in which the means for moving workpieces includes a stop element supported adjacent the adjustable cutter for locating workpieces of different lengths in the same cutting position with respect to the adjustable cutter when the latter member is advanced to an engaging position.

6. A structure according to claim 1 in which the means for moving workpieces includes a stop element supported adjacent the adjustable cutter for locating workpieces of different lengths in the sa-me cutting position with respect to the adjustable cutter when the latter member is advanced to an engaging position and said stop element including a switch element projecting from one side thereof in a position to be contacted by a workpiece prior to engagement with the stop element.

7. Apparatus for machining workpieces which are formed with a surface to be machined, Said apparatus including means for feeding workpieces in a randomly oriented state, a sensing and positioning device for receiving workpieces and releasing each of the workpieces with its surface to be machined positioned in a predetermined state of orientation, said sensing and positioning device including an inclined workpiece guideway, a workpiece receptacle located at the bottom of the said guideway and being formed with a movable trap door, fluid pressure operated means for selectively opening the trap door, means in the receptacle for engaging a workpiece and turning it into a desired position when the trap door is opened, an indexing member formed with a plurality of adjustable collets for releasably holding workpieces and moving them through a plurality of work supporting stations, and a cutter mechanism movable into and out of cutting engagement with workpieces in one of the work supporting stations.

References Cited UNITED STATES PATENTS 405,152 6/1889 Euston 10-162 1,564,576 12/1925 Kahrs et al 10-162 1,864,450 6/1932 Lozier 10-21 2,589,590 3/1952 Woolcott -56 2,662,626 12/1953 Graham et a1. 10-162 3,056,981 10/1962 Byam 10-21 3,289,884 12/1966 Klancnik 10-162 GERALD A. DOST, Primary Examiner.

US. Cl. X.R.

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